This invention relates to a programmable precision locator apparatus or unit which is commonly used along a linear conveyor for transferring or indexing parts, such as vehicle underbody panels or vehicle bodies through a series of work stations or cells along the conveyor where different operations, such as clamping and spot welding, are performed on the parts at the stations. Commonly, in manufacturing lines for motor vehicles, a plurality of programmable precision locating apparatus or units are positioned under a conveyor system. Each precision locating unit supports a horizontally and vertically adjustable locating pin and clamp device which is positioned to engage and clamp a hole within the body or body panel and then lift the body part to an elevated position where welding or other operations are performed on the part while the part is held in a precise fixed position.
One such precision locating apparatus or unit which has been used in the manufacture of vehicle bodies and body panels is produced by Fanuc Robotics North America, Inc. and sold under the trademark FLEXTOOL. The construction of such a programmable positioner is disclosed in U.S. Pat. No. 6,425,177. Another type of programmable positioner is sold by General Motors Corporation under the trademark PAAS. This positioner is capable of five different types of articulation. That is, the entire unit may move horizontally, vertically and rotate about a vertical axis. The tooling attachment may also be rotated around both vertical and horizontal axes. The positioner is also marketed by Fanuc Robotics North America, Inc. under the trademark C-FLEX.
The programmable positioners described above are commonly positioned under a linear part conveyor and thus require an elevated part conveyor which is relatively expensive to construct and maintain in comparison to a less expensive power roll bed conveyor or other low cost part handling device located on the floor. The programmable positioners described above are also complex in construction and are limited in their lifting capacity. It has also been found desirable for the programmable positioners to avoid the use of fluid cylinders such as air and hydraulic cylinders and the associated equipment for producing and supplying pressurized air or pressurized hydraulic fluid.
In general, programmable precision locating units are especially desirable in the manufacture of motor vehicle parts such as underbody panels or complete vehicle bodies so that different styles or types of body panels or complete bodies may be produced on the same manufacturing line. That is, the units provide for quickly relocating precision locating pin and clamp devices for engaging locating holes within the different body panels or complete bodies being conveyed along the manufacturing line.
Usually, a plurality of the precision locating units supporting corresponding locating pins and clamp devices are positioned under a body panel or complete body supported by the conveyor. The units are simultaneously operated to elevate the locating pins to engage corresponding holes within the panel or body. The units then lift the body or body panel up from the conveyor to a position where the panels and any parts to be added are clamped together, after which robotic spot welders weld the panel and parts together. At a down stream work station or cell along the part conveyor, another group of the precision locating units may be used for additional spot welding of the parts. The units are also used at a work station or cell for body framing where the underbody panels are joined with body parts such as side frames, inner and outer quarter panels, roof bows which are brought together for spot welding in order to form a complete vehicle body.